This invention relates to a time detecting device of an alarm clock and more particularly to the improvement of the alarm time detecting mechanism having a projection formed on either the time gear wheel or the alarm gear wheel and a cavity formed on the other.
In the conventional detecting mechanism of this type, the related parts of the projection and the cavity are formed by vertical faces to provide a high accuracy of detection in generating a detection signal when the projection falls into the cavity at an alarm time. Thus, in setting the conventional alarm mechanism, if the alarm gear wheel is turned in the direction that the vertical faces are engaged with the projection fallen into the cavity, the hour wheel is forcedly pushed and turned resulting in dislocation of time indication, or a part of the vertical faces is damaged when the hour gear wheel is hard to turn because of the resistance of the related gear trains. Accordingly, it is usual to provide a reversing check mechanism to prevent the turning of the gear wheels in the direction as described above. However, such mechanism still has disadvantages that the reversing check mechanism may be broken by mishandling, such as by forcedly turning the mechanism in the wrong direction, or a little reverse turning damages the vertical faces.